The present invention relates to an alloy for disk rotor utilized in disk brake, in particular, the alloy for disk rotor which is utilized in the disk brake for the braking of cars and which has an ability to dampen the vibrations and a high strength.
For the braking of cars, the disk brake is used widely. The disk brake is constructed so that the braking force can be exerted by pressing a pair of friction pads provided in a state that they are opposite to the both sides of disk rotor rotatable together with the wheels against said both sides of disk rotor by means of hydraulic piston.
Now, with such disk rotor utilized in the disk brake, the small vibrations are inevitable at the time of braking due to the friction engagement with friction pads and, when these vibrations become large, it comes to generate the noise offensive to the ear.
For this reason, as the metal which constitutes the disk rotor, an alloy high in the damping factor of vibrations has been used hitherto and the vibrations generating upon braking due to the friction engagement with friction pads have been made not to grow so large as generating the noise offensive to the ear.
As such alloy high in the damping factor of vibrations for constituting the disk rotor, one containing 2.5 to 2.8 wt.% of silicon, 0.5 to 0.9 wt.% of manganese, 0 to 0.3 wt.% of chromium, 0 to 0.3 wt.% of copper and 3.4 to 4.0 wt.% of carbon, the remainders being inevitable impurities and iron, has been used widely hitherto.
However, the conventional alloy for disk rotor having the composition as mentioned above has low tensile strength in place of the high damping factor of vibrations, thus it was not necessarily possible to obtain sufficient strength when utilized in the disk brake used under severe conditions.
The alloy for disk rotor of the invention aims at that, by retaining the high damping factor of vibrations while improving the tensile strength, the inconvenience aforementioned is dissolved.